Method for producing alkali metal xanthates



liatented Aug. 23, 1932 UNITED STATES P ATEN-T oF FrcE LUDWIG ROSENSTEIN, OF SAN FRANCISCO, CALII FORNIA,VASSIGNOR 'I'O GREAT WES T ER'N" ELECTED-CHEMICAL COMPANY, OF SAN FRANCISCO, CALIFORNIA, .A, CORPORATION on CALIFORNIA No Drawing,

This invention relates to a method "for the manufacture of alkali metal xanthates; and its'object is toproduce these compounds 1n considerable quantities upon a commercial metal xanthates which will effectively complete the reaction with substantially the theoretical amounts of the various substances used, and with the minimum loss of material due to incompleted reactions.

The method which is the subject of this invention aims to bring about reaction between thecomponents in nearly theoretical amounts and to produce the xanthates largely in the solid form at once. This isaccomplished by first bringing about a reaction between an alkali metal hydroxide such as potassium hydroxide with commercial alcohol by heating the two together in a closed vessel from which no alcohol can escape as vapor. Under these conditions a pressure is naturally built up, the magnitude of which depends on the temperature to which the heating is carried, and the proportion of alcohol employed to a unit weight of the alkali metal hydroxide. Under the conditions described a reaction probably takes place between the a1- kali metal hydroxide and the alcohol to form water and some alkali metal ethylate, but this reaction will not proceed to completion. When the ingredients in the above described closed vessel are now cooled they will be found to consist of a semi-solid mass containing some alkali metal ethylate, alkali metal hydroxide with both water and alcohol of crystallization and a solution of the alkali metal hydoxide'in any excess of alcohol originally employed.

The process is not concerned wlth the completeness of the alcohol plus alkali metal hydroxide reaction more than to note that METHOD ma PRODUCING ALKAIL'I eme Application fil ed 'Novein'ber 12,1924, Serial 110,749,558

when the hydroxide is completely mechani}. cally disintegrated with the proper a ount of alcohol that the carbon bisulphide reaction will proceed smoothly and rapidly to com pletion in a way thatis commercially prac ticable. In fact it is not possible to correct ly determine just what is produced byithis first reaction, except that the bulk of the a1 kali'while unchanged in composition'has'beeni so changed physically as to readily react with; the carbon bisulp hide in' the next step. I

The mass above described when mixedwith the proper amount of carbon bisulfide, reacts smoothly andjwith considerable heat evolution to' form alkali-metal xanthate, largely in a solid form. The separation and drying of the crystals, thereof may thenbe' carried out in any well known manner. 1

Since the purpose of this invention 'is to bring about the reaction which leadstothe formation of alkali metal xanthates between substantially the theoretical quantities of r'eagents it is best practiced by placing in the;- above described closed Vessel foreach grain molecular weight of alkali metal xan thatei one kilogram molecular weight of the alcohol-to be used. A larger amount'of also: hol than inthe above proportion is often found convenient since it makes a mass more fluid and easier to stir,'but in this case the excess of alcohol over the ratio above named? isremoved by distillation after the'mass has beenfheated under pressure as described,- and; before adding the carbon bisulfide.

The alkali metal hydroxide may be finely gi'pund for convenience as this hastens fl'akefor even in a molten condition, theessential point being that 'it is first brought into combination with an alcohol" inthe proportion of the molecularweights .by theuti lizationfo'f heat and pressure. i

One example of a practical method of 'ryin'g out this invention is as'fol'lowsz' T060 kilograms of ground caustic potash grams ofcommercial denatured ethylalfco-l holgf The autoclave is-now heatedwiththe vent cock open until alcohol-vapors escape therefrom-which indicates that the air has been completely displaced. The vent cock is now closed and heat applied until the pressure reaches about 150 lbs. It is held at this pressure for one and one-half hours, after which the heat is shut oii" and the autoclave cooled'until the mass contained in-it is barely fluid enough to move. To it isthen added, with stirring and cooling, kilograms carbon bisulfide." When the reaction forming i xanthateis completed the mass is spun dry in a centrifugal machine, and the crystals of potassium xanthate dried or further purified. There will be obtained about -k-i-lo-- grams of commercial potassium xanthate. I The temperature of the reacting mass when the carbon bisulphide is added should be kept below the atmospheric boiling point of the bisulphide. i

tions may-be made incarrying out the in vention as defined by the annexed claims:

1. A method of producing alkali metal xanthate which consists of heating an alkali metal hy'dro xide with an excess of alcohol in a closed system at a temperature capable of producing a pressure of about pounds to the square inch maintaining said pressure fora period of time to cause the substantial disintegration of the hydroxide by the alcohol, cooling the mass and then carbon bisulfide thereto. r

2. A method of producing alkali metal xanthates'which consists in heating an alkaliymetal hydroxide and an alcohol in a closed system at a temperature capable of producing a pressure of substantially 1570 vpounds tov the square inch, maintaining that pressure and temperature fora period of time to cause the substantial disintegration of the hydroxide by the alcohol, cooling themass, then adding carbon bisulphide thereto and finally drying the xanthate product. 3. A method of producing alkali metal xanthates which consists in placing an, alkali vmetal hydroxide in a closed system with anv excess of alcohol, heating the materialto a temperature capable of producing a pressure above atmospheric for a sufficient time to effect a reaction of the materials and to disintegrate the hydroxide, removing the excess of alcohol by distillation, cooling the mass, adding carbon bisulfide thereto, While maintainingthe mass belowthe decomposition pointed of the xanthate to be produced.

A. method of producingalkali metal xanthates which. consists in placing an alkali metal hydroxide in a closed receptacle with an excess of alcohol, heating the material until a temperature capable of roducing a; pressure of about. 150 lbs. to the squareinch is produced,-maintaining that 7 pressure and temperature until the disinte- 'tillation, cooling the, mass, adding YCflIbOIIi What. I claim is as follows, but modificaadding bisulfide thereto, maintaining the mass at a temperature below the decomposition point of the xanthate to be produced then drying the solid alkali metal xanthate produced.

. 5. A. method of producingvalkali metal xanthates which consists in dispersing an alkali metal hydroxide in an alcohol with the wtwmms mm ee 

